Membrane bioreactors (MBRs) are frequently used for treating wastewater. An MBR combines biological treatment processes with membrane filtration to provide organic and suspended solids removal. These systems typically provide an advanced level of nutrient removal. Membrane filtration processes provide high quality effluent to be transported through the membranes and generally function similarly to sedimentation and filtration processes. Because the need for sedimentation is eliminated, the biological process can operate at much higher mixed liquor suspended solids concentrations.
One type of conventional system includes at least one biological reactor and a membrane filtration tank disposed downstream from the reactor. A membrane module or cassette is typically submerged in the filtration tank. Mixed liquor is transferred from the reactor to the downstream filtration tank. The membrane module or cassette typically includes an array of submerged individual membrane filters. Mixed liquor is induced into the open space between the individual membrane filters, resulting in the mixed liquor being filtered and producing a permeate. The permeate is pumped or is flowing by gravity from the individual membrane filters and the filtration tank.
MBR systems are typically constructed out of stainless steel and membrane cartridges connected to a stainless steel manifold where water is pumped out of the cartridges via the manifold pipe connections to the cartridges. This solution is expensive and is designed for huge monolithic systems that are expected to handle a high volume of wastewater and stay fixed in one location for tens of years. Typically the cost of the MBR frame ranges in the 20-20% of the total cost of the MBR system.
Descriptions of certain details and implementations follow, including a description of the figures, which may depict some or all of the embodiments described below, as well as discussing other potential embodiments or implementations of the inventive concepts presented herein. An overview of embodiments of the invention is provided below, followed by a more detailed description with reference to the drawings.